I'm not entirely confident in the statistical method I am using for my study design, and would like some feedback/advice.
I am primarily looking at the effect of land use on stream chemistry parameters, however, I also want to examine the significance of season and stream flow. To test this, I developed a nested design. I have three land cover types, and I sampled five streams within each land cover 20 times. These 20 samples at each stream were taken during each season, some at high and some at low flows.
I understand (or think I do) that, as a nested design, it would make sense to use a mixed-effects model with land cover as a fixed effect:
land cover + (1|stream ID)
But I would like to add flow and season as variables and create more complex models before comparing them using AIC, but I'm not exactly sure what they would look like? Something like:
flow + season + land cover + (1|stream ID) ???
Any suggestions would be appreciated!